• synonyms


[plan-i-tair-ee-uh m]
noun, plural plan·e·tar·i·ums, plan·e·tar·i·a [plan-i-tair-ee-uh] /ˌplæn ɪˈtɛər i ə/.
  1. an apparatus or model representing the planetary system.
  2. a device that produces a representation of the heavens by the use of a number of moving projectors.
  3. the building or room in which such a device is housed.
Show More

Origin of planetarium

1765–75; < New Latin, noun use of neuter of Latin planētārius planetary; cf. -arium
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for planetarium

Historical Examples

  • The planets are visible during the day in the planetarium as well as night.

    Astounding Stories, August, 1931


  • Ingulfus mentions at the same time a nadir, as he calls it, or planetarium, executed in various metals.

  • In the school-room there was a planetarium, very neatly finished, set in motion by clock-work.

    Travels Through North America, v. 1-2

    Berhard Saxe-Weimar Eisenach

  • The dome was lighted to represent a clear night, and, incidentally, all nights are clear in a planetarium.

British Dictionary definitions for planetarium


noun plural -iums or -ia (-ɪə)
  1. an instrument for simulating the apparent motions of the sun, moon, and planets against a background of stars by projecting images of these bodies onto the inside of a domed ceiling
  2. a building in which such an instrument is housed
  3. a model of the solar system, sometimes mechanized to show the relative motions of the planets
Show More
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for planetarium


1734, "orrery," Modern Latin, from Late Latin planeta (see planet) + Latin -arium "a place for." Sense of "device for projecting the night sky onto the interior of a dome" is attested from 1929.

Show More
Online Etymology Dictionary, © 2010 Douglas Harper